Dim ingnition warning lamp

[Minornut59]

Hi all,

My 1967 saloon had an alternator fitted by a previous owner and for the past 7 years it has given no trouble. The control box is present on the bulkhead but is discnnected entirly save for the earth wires.

Just recently i noticed that the ignition warning lamp is glowing very dimly at all engine speeds. I have a voltmeter fitted to the dash and this reads around 13.5volts at fast idle with no accesories switched on as it always has since i fitted the gauge.

The battery seems to stay charged and the car starts readily enough.

At night with halogen lamps, heater, stereo, and wipers where necessary swiched on, all seems normal and she'll start the next morning ok.

However, over the past two years on very rare occasions i have found the car to be completely flat; ie; the battery has been dead. Initially this was down to the nine year old battery which died suddenly and i replaced, and then the new one packed in within a year due to a dodgy cell; and was replaced under warranty. When i had the same trouble again, i did a parasitic drain test and found that some current was being drained off by the stereo. With the stereo disconnected there was no drain showing on the meter and after a week or two I changed this for another stereo and have had no further trouble with flat batteries since August.

Now i am wondering if the root cause of all this was actually the alternator.

The car is in regular use and the flat battery problem in the past has only occurred after the car has been left for three or four days while i used my other Morris or my Austin.

If the lamp is glowing this points to the alternator doesn't it, but the red light comes on normally and goes out when starting, but instead of going out completely it just glows very faintly. When switching off, it will flare up before the engine dies, which seems normal.

Any thoughts?

[bmcecosse]

Well - it's not right as you know - but if there is no drain when idle, and it still holds that 13.5 volts with lights/heater/wipers on - then don't worry about it. You could check the fan belt is tight enough - but I doubt it's the problem.

[mike.perry]

The ignition warning light on my *Maxi glowed for years with no obvious defect
*Best passion wagon ever built. It had a double bed which folded up to make seats if you had the misfortune to have to drive the thing.

[Minornut59]

Funny, i only saw a Maxi yesterday! That choccy brown colour... I have always had a soft spot for those 70's BL cars. I have a 73 Austin 1300 that has managed to survive lots of rust and repairs. I even replaced the roof guttering a few years back.

Anyway, took the Minor on a 100 mile round trip yesterday and today and it was all normal, so i am going to keep an eye on it. I did nticed that once yesterday the lamp glowed momentarily brighter when i revved up, and i began to wonder 'carbon brushes' to myself. I wonder if they are on the way out and thats why the lamp is glowing?

[bmcecosse]

Yes - it's possible. Get a set of brushes in stock asap..

[kennatt]

It could be a dodgy regulator,could last for years,or not. If it's an acr you can get new regulators from E Bay for about £10 and very simple to replace,just need very small and narrow socket to get the cover off.

[Minornut59]

Well, the light got a bit brighter, so i whipped it off and put another alternator on. When stripped th first unit down i found one of the carbon brushes was worn down to 4mm; the manual says 7mm minimum. So i think i may try some new brushes and see if that fixes it.

[bmcecosse]

The outer circle brush always wears away long before the inner brush. One new brush well worth trying!

[kennatt]

worth a try,but had exactly the same fault On mine even after new brushes ,a new regulator cured it.